Yoshiaki Murakami, who once struck fear into Japan’s boardrooms and split public opinion with bitter activist battles, is now enjoying rare acclaim from executives and being praised as a peacemaker.

Murakami, an outspoken champion of shareholder rights before his conviction for insider trading, has emerged as the key figure in pushing through the merger of refiners Idemitsu Kosan Co. and Showa Shell Sekiyu K.K.

Murakami served as a consultant to Idemitsu’s founding family, whose dispute with executives held up the merger, and persuaded them to accept the integration with a series of concessions for shareholders.

So influential was his role that Idemitsu Chairman Takashi Tsukioka publicly praised him at a news conference in Tokyo last week. Murakami, who ruffled feathers in Japan in the 2000s with controversial takeover attempts and activist campaigns and now lives in Singapore, says he always had Japan’s best interests at heart.

“I think it’s a good thing, I really do,” Murakami said of the resolution, speaking in a rare phone interview after years of avoiding the media. “This merger contributes to Japan’s energy security.”

Idemitsu and Showa Shell shares have surged since reports last month that the merger, first mooted almost four years ago, was back on the cards. The two companies will now combine in 2019.

Murakami says a person in the financial industry, whom he declined to identify, asked him to advise the founding family last fall.

“I wanted to help if I could,” Murakami said. “I thought it was extremely important that Idemitsu and Showa Shell merged.”

He’s also likely to see a tidy return on his investment in Idemitsu, which has risen almost 30 percent since reports of his involvement first emerged in May. Murakami says he didn’t care about purchasing the stock, and only bought it so he could enter the talks as a fellow shareholder.

Idemitsu’s founding family was always looking out for the company’s interests, according to Murakami, and its position was never that far from the oil refiner’s. He says the firm’s executives should have explained the situation better.

“There was a slight misunderstanding between the company and the founding family,” he said. “I realized there was no big gap after I talked to management.”

In a statement, a lawyer representing the family acknowledged Murakami’s “valuable efforts” in securing an explanation from Idemitsu’s management.

Murakami had a turbulent relationship with his home country after he quit his career as a bureaucrat in 1999 to establish his own fund. He made headlines with the first hostile takeover bid by a Japanese investor, then demanded companies including the operator of the Osaka Securities Exchange increase shareholder returns.

In 2007 he was convicted of insider trading and sentenced to two years in prison, which was suspended on appeal.

The Financial Securities Agency launched a probe in 2015 into allegations he manipulated stock prices, though it was said to be dropped without charges earlier this year. Murakami denied the allegations.

These days, Murakami invests only his own funds. With no investors to think about, he says he has time to consider ways to contribute to society. Most recently, he’s been helping with the fallout from the flooding in western Japan.